From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB4D0C433E0 for ; Mon, 11 Jan 2021 13:40:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9EAFC221FD for ; Mon, 11 Jan 2021 13:40:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732954AbhAKNji (ORCPT ); Mon, 11 Jan 2021 08:39:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:46550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731760AbhAKNjY (ORCPT ); Mon, 11 Jan 2021 08:39:24 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BC595221FD; Mon, 11 Jan 2021 13:38:43 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1kyxFF-006gPD-JI; Mon, 11 Jan 2021 13:28:29 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , Mark Rutland , David Brazdil , Alexandru Elisei , Ard Biesheuvel , Jing Zhang , Ajay Patil , Prasad Sodagudi , Srinivas Ramana , James Morse , Julien Thierry , Suzuki K Poulose , kernel-team@android.com Subject: [PATCH v3 12/21] arm64: cpufeature: Add an early command-line cpufeature override facility Date: Mon, 11 Jan 2021 13:28:02 +0000 Message-Id: <20210111132811.2455113-13-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210111132811.2455113-1-maz@kernel.org> References: <20210111132811.2455113-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, dbrazdil@google.com, alexandru.elisei@arm.com, ardb@kernel.org, jingzhangos@google.com, pajay@qti.qualcomm.com, psodagud@codeaurora.org, sramana@codeaurora.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In order to be able to override CPU features at boot time, let's add a command line parser that matches options of the form "cpureg.feature=value", and store the corresponding value into the override val/mask pair. No features are currently defined, so no expected change in functionality. Signed-off-by: Marc Zyngier --- arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/head.S | 1 + arch/arm64/kernel/idreg-override.c | 119 +++++++++++++++++++++++++++++ 3 files changed, 121 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/idreg-override.c diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 86364ab6f13f..2262f0392857 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -17,7 +17,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ return_address.o cpuinfo.o cpu_errata.o \ cpufeature.o alternative.o cacheinfo.o \ smp.o smp_spin_table.o topology.o smccc-call.o \ - syscall.o proton-pack.o + syscall.o proton-pack.o idreg-override.o targets += efi-entry.o diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index d74e5f84042e..b3c4dd04f74b 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -435,6 +435,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) mov x0, x21 // pass FDT address in x0 bl early_fdt_map // Try mapping the FDT early + bl init_shadow_regs bl switch_to_vhe #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) bl kasan_early_init diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c new file mode 100644 index 000000000000..392f93b67103 --- /dev/null +++ b/arch/arm64/kernel/idreg-override.c @@ -0,0 +1,119 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Early cpufeature override framework + * + * Copyright (C) 2020 Google LLC + * Author: Marc Zyngier + */ + +#include +#include + +#include +#include + +struct reg_desc { + const char * const name; + u64 * const val; + u64 * const mask; + struct { + const char * const name; + u8 shift; + } fields[]; +}; + +static const struct reg_desc * const regs[] __initdata = { +}; + +static int __init find_field(const char *cmdline, const struct reg_desc *reg, + int f, u64 *v) +{ + char buf[256], *str; + size_t len; + + snprintf(buf, ARRAY_SIZE(buf), "%s.%s=", reg->name, reg->fields[f].name); + + str = strstr(cmdline, buf); + if (!(str == cmdline || (str > cmdline && *(str - 1) == ' '))) + return -1; + + str += strlen(buf); + len = strcspn(str, " "); + len = min(len, ARRAY_SIZE(buf) - 1); + strncpy(buf, str, len); + buf[len] = 0; + + return kstrtou64(buf, 0, v); +} + +static void __init match_options(const char *cmdline) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + int f; + + if (!regs[i]->val || !regs[i]->mask) + continue; + + for (f = 0; regs[i]->fields[f].name; f++) { + u64 v; + + if (find_field(cmdline, regs[i], f, &v)) + continue; + + *regs[i]->val |= (v & 0xf) << regs[i]->fields[f].shift; + *regs[i]->mask |= 0xfUL << regs[i]->fields[f].shift; + } + } +} + +static __init void parse_cmdline(void) +{ + if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) { + const u8 *prop; + void *fdt; + int node; + + fdt = get_early_fdt_ptr(); + if (!fdt) + goto out; + + node = fdt_path_offset(fdt, "/chosen"); + if (node < 0) + goto out; + + prop = fdt_getprop(fdt, node, "bootargs", NULL); + if (!prop) + goto out; + + match_options(prop); + + if (!IS_ENABLED(CONFIG_CMDLINE_EXTEND)) + return; + } + +out: + match_options(CONFIG_CMDLINE); +} + +void __init init_shadow_regs(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + if (regs[i]->val) + *regs[i]->val = 0; + if (regs[i]->mask) + *regs[i]->mask = 0; + } + + parse_cmdline(); + + for (i = 0; i < ARRAY_SIZE(regs); i++) { + if (regs[i]->val) + __flush_dcache_area(regs[i]->val, sizeof(*regs[i]->val)); + if (regs[i]->mask) + __flush_dcache_area(regs[i]->mask, sizeof(*regs[i]->mask)); + } +} -- 2.29.2